With the rapid development of China's modernization process and the power industry, the low-voltage electrical technology is developing continuously. Accordingly, more and more function-integrated small-sized low-voltage electrical appliances come forth. The low-voltage circuit breaker has been widely used. The low-voltage circuit breaker, which is a switching device, not only can connect and break the normal load current and the overload current, but also can connect and the break short-circuit current. In the circuit, the low-voltage circuit breaker can perform a control function and certain protection functions, such as the protection of overload, short circuit, under voltage, leakage, and so on. The low-voltage electrical appliances have become the mainstream devices for the future development of the circuit breakers. ACB is an acronym for Air Circuit Breaker. Among others, the frame-type circuit breaker (also referred as frame breaker) is a low-voltage switch appliance with a large capacity. In the distribution system, the frame-type circuit breaker is used to connect and break the normal current. Under the condition of failure, i.e., when the circuit is abnormal, the circuit is automatically cut off by the frame-type circuit breaker to protect the lines, and equipment, and for personal safety. In the frame-type circuit breaker, the functional block which triggers an operation mechanism to cut off the circuit in response to a fault current is called the tripping device. In order to prevent the circuit breaker from being tripped or inserted in a power-on state, it is necessary to provide a mechanical interlocking mechanism. The function of the mechanical interlocking mechanism is described as follows. During the tripping operation of the circuit breaker, the tripping device is controlled by the mechanical interlocking mechanism to be tripped and switched off before the circuit breaker reaches the disengaged position from the coupling position. During the inserting operation of the circuit breaker, the tripping device is controlled by the mechanical interlocking mechanism for maintaining the tripping and switching-off state before the circuit breaker reaches the coupling position from the disengaged position. The practice has proved that the usage current frame-type ACB tripping devices have certain security risks. When the circuit breaker is installed into the drawer seat, if the switch is closed to power on at the time that the circuit breaker does contact the drawer seat reliably, sparks will be generated between the contacts. In a severe case, the circuit breaker may be burnt, which will cause a great security risk.